Herbicide sodium trichloroacetate

Sodium trichloroacetate [650-51-17, C2Cl202Na, is used as a herbicide for various grasses and cattails (2). The free acid has been used as an astringent, antiseptic, and polymerisation catalyst. The esters have antimicrobial activity. The oral toxicity of sodium trichloroacetate is quite low (LD q rats, 5.0 g/kg). Although very corrosive to skin, trichloroacetic acid does not have the skin absorption toxicity found with chloroacetic acid (28). 

The same applies to sodium trichloroacetate CClsCOONa, an herbicide known under the reference TCA, the solutions of which strongly attack aluminium. 

It is estimated that over 100,000 acres in Hawaii and some 250,000 acres in Louisiana each year are treated with herbicides, mostly 2,4-D and TCA (sodium salt of trichloroacetic acid), for pre- and postemergence weed control. Johnson grass on ditch banks on some 50,000 to 75,000 superficial acres in Louisiana is controlled with sodium chlorate or TCA. Some trials with CMU [3-(p-chlorophenyl)-l,l-di-methylurea] are in process. Florida cane growers use 150,000 pounds of 2,4-D amine salt of Karmex W on 43,000 acres of cane and anticipate using up to 100,000 pounds per year. Of the growers in Puerto Rico, 60% are said to use herbicides as either pre- or post-emergence sprays. 

Two aliphatic acids possess, for grasses, many of the growth-distortion and toxicity effects associated with the synthetic auxins on dicotyledonous plants. Trichloroacetic acid and 2,2-dichloropropionic acid (dalapon), as the sodium salts, have been called grass "hormones or auxins, although Wilkinson184 could find no growth stimulation at low concentrations, and described dalapon as an antiauxin from its interference with indole-3-acetic acid effects. The herbicidal properties of trichloroacetate do not depend on its protein-denaturing ability, and those of 2,2-dichloropropionic acid involve, at least indirectly, the synthesis of pantothenic acid. 

The Frank and Demint [200] method is directly applicable to water samples. After addition of sodium chloride (340g IT1) and aqueous hydrochloric acid (1 1) to bring the pH to 1, the sample was extracted with ethyl ether and the organic layer was then extracted with 0.1M sodium bicarbonate (saturated with sodium chloride and adjusted with sodium hydroxide to pH8). The aqueous solution adjusted to pHl with hydrochloric acid was extracted with ether and after evaporation of the ether to a small volume, Dalapon was esterified at room temperature by addition of diazomethane (0.5% solution in ether) and then applied to a stainless steel column (1.5m/3mm) packed with Chromosorb P (60-80 mesh) pretreated with hexamethyldisilazane and then coated with 10% FFAP. The column was operated at 140°C, with nitrogen carrier gas (30mL muT1) and electron capture detection. The recovery of Dalapon ranged from 91 to 100% the limit of detection was O.lng. Herbicides of the phenoxyacetic acid type did not interfere trichloroacetic acid could be determined simultaneously with Dalapon. 

Sodium chlorate Sodium chloride Sodium isopropyl xanthate Sodium metaborate Sodium pentachlorophenate N-Tallow-1,3-diaminopropane dioleate Tebuthiuron Terbuthylazine Tetrahydroxypropyl ethylenediamine Triallate Trichloroacetic acid 2,4,6-Trichlorophenol Trietazine Xylenol herbicide additive Humic acid... 

Trichloroacetic acid, CCI3-COOH, is produced by chlorination of acetic acid at 140 -160 °C and purified by crystallization. The sodium salt is used as herbicide. 

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